74 



THE NERVOUS SYSTEM 



established the existence of a differentiation which 

 has almost revolutionised cerebral physiology, and 

 has vastly extended the range of cerebral diagnosis. 

 The first step of the new discovery was constituted 

 by the clinical and pathological observations of 

 Hughlings Jackson, which suggested the existence, 

 on each side of the fissure of Rolando, of special 

 centres for the movements of the leg, arm, and face. 

 These observations led to the experiments of Ferrier, 

 which resulted in the demonstration of the existence 

 in the cortex of the lower animals of well-defined 

 regions, stimulation of which caused separate move- 

 ments, or evidence of special sense excitation, while 

 the destruction of the same parts caused indications 

 of a loss of the corresponding function. Hence he 

 came to the conclusion that these regions constitute 

 actual motor and sensory centres. Ferrier had, 

 however, been anticipated in many of these results 

 by two German experimenters, Fritsch and Hitzig, 

 whose results, differing a little in detail, correspond 

 closely in their general significance. Many other 

 investigations of the same character have since 

 been made, of which those of Munk are especially 

 important. The original observations of Hughlings 

 Jackson left little doubt that the general facts, 

 learned from experiments on animals, are true of 

 man ; and this conclusion has been to a large 

 extent confirmed by pathological and clinical obser- 

 vations directed to the verification on man of the 

 pathological results. To this verification the 

 labours of Charcot and his coadjutors have largely 

 contributed. But the verification has already made 

 it probable that some differences exist between the 

 brain of man and that of higher animals (even of 

 monkeys), and that the conclusions from the latter 

 cannot be simply transferred to the former." 



